On Jan 26, 2009, at 10:11 PM, Barry Margolin wrote:
In article <gllr91$2vq...@sf1.isc.org>,
Scott Haneda <talkli...@newgeo.com> wrote:
I have never got why this is such a hard thing for email admins to
get
right, but it certainly causes me headaches. I personally wish
CNAME's would just go away, keep them around, but just stop talking
about them, then new to DNS users would not use them.
Suppose you're providing an MX service, but you actually out-source
the
operation to a third party. You want to give your customers an MX
record that points to a name in your domain, so they don't need to
know
about the third party (and so you have the flexibility to change your
out-sourcing without requiring all customers to update their MX
record).
But the third party also needs the flexibility to change the IP of the
server, load balancing, disaster recovery, changing ISPs, etc. So
they
don't want you to hard-code their IPs into your domain.
CNAMEs are the simplest solution to implementing all this.
customer.com. IN MX 10 mx.yourdomain.com.
mx.yourdomain.com. IN CNAME mx.outsourcer.com.
mx.outsourcer.com. IN A ...
If the customer changes MX services, they change their MX record. If
you change outsourcing companies, you change your CNAME record. And
if
the outsourcing company re-IPs their server, they change the A record.
Everyone can perform their job without having to make any of the
downstream customers adjust their records.
Totally valid points, I agree with them all. And it is these points
that I was talking about when I suggested CNAME's go away. Not really
go away, but the above case is clearly one in which the admin knows
that they are doing.
What my trouble is, is with the mail admins who clearly do not, and
then argue about solving it. I better example is servers that do not
support greylisting, and bounce on 450 code. This is pretty simple,
and obvious as to why you need to try in a transient error like that.
Anyway, not saying I disagree with you, I do not, but I was just
venting a little.
--
Scott
_______________________________________________
bind-users mailing list
bind-users@lists.isc.org
https://lists.isc.org/mailman/listinfo/bind-users
